Fructose Infusion Research Articles

Comparative Utilization of Intravenous Fructose and Invert Sugar

Summary 1.Total 24-hour urinary losses of sugar were studied following inf usion of 10 per cent fructose and of 10 per cent invert sugar at rates of 1000 ml. per hour and 1000 ml. per 2.5 hours in normal subjects on alternate days, each patient thus serving as his own control. The average losses were 3.8 per cent to 7.1 per cent of the total amount infused, with a maximum of 11.4 per cent in any single patient. 2.The average amount of sugar excreted in the urine is less at the slowerrate of infusion with both sugars. 3.At each infusion rate, less sugar is excreted with fructose than with invertsugar, and the difference is largely due to the larger loss of glucose in the urine following infusion of invert sugar. Fructose given at a rate of 1000 ml. per 2.5 hours was most efficiently retained. 4.The results of this study suggest that 10 per cent invert sugar is notutilized as if the 5 per cent fructose and 5 per cent glucose components were treated independently by the body, but rather that the urinary sugar losses lie between those anticipated with 10 per cent fructose alone and 10 per cent glucose alone. There is certainly no suggestion of a favorable effect of one sugar on the other and retention of fructose is even less than would be expected had it been given alone. 5.Fructose and invert sugar infused into patients with widespread cancerbehave much as they do in normal subjects, although losses are somewhat greater, particularly at more rapid infusion rates. However, losses of glucose far in excess of those seen in normal patients after infusions of fructose were observed in 2 cases, suggesting abnormal conversion of fructose to glucose. 6.After major operations, infusions of both fructose and invert sugar areefficiently retained, just as in the case of normal patients. One patient excreted an unusual amount of glucose in the urine after infusions of fructose. 7.Postoperative urinary losses of sodium and potassium are of the ordernoted in previous studies with glucose infusion or with no infusion. Average losses of sodium were slightly higher with fructose than with invert, but in neither case is the loss exceptional (56.9 mEq. and 39.8 mEq.).

POSTOPERATIVE LOSS OF SUGAR IN URINE FOLLOWING INTRAVENOUS INFUSION OF FRUCTOSE (LEVULOSE)

IN A PREVIOUS report 1 the urinary losses of sugar following the intravenous infusion of fructose (levulose) and of D-glucose (dextrose) were compared in an unselected group of patients. In the present study a similar comparison was made in patients during the immediate postoperative period. No other observations have been reported thus far on the behavior of fructose given by intravenous infusion after operation. METHODS Observations were made in two groups of patients. In the first group there were 10 patients all well nourished and undergoing various major surgical procedures under general anesthesia. During each of the first four postoperative days, 2 liters of 10% sugar was infused, using on alternate days 10% fructose 2 and 10% dextrose. On the first day, six patients were given dextrose and four fructose. An attempt was made to give each infusion at the same rate, but in each case the duration was measured

The utilization of fructose by human subjects and animals.

Abstract Tolerance studies in human subjects receiving 47 or 50 Gm. of fructose in 1,000 ml. of distilled water at an average rate of 0.76 Gm. per kilogram per hour showed 1.1. Fructose is rapidly removed from the blood. With a continuous intravenous infusion of fructose, the second 25 or 23.5 Gm. are removed from the blood at practically the rate of infusion. 2.2. Low levels of hyperglycemia and a rapid return to normal blood sugar levels were seen. After the infusion of the first 25 Gm. of fructose, the average value for reducing substances in the blood was 144.5 mg. per cent, and at the end of the 50 Gm. infusion, the average value was 143.9 mg. per cent. One hour later the circulating blood sugar levels were similar to the preinfusion values. 3.3. A portion of the injected fructose appears to be converted to glucose, and the latter is detectable in the blood during the period of infusion. Fortyseven per cent of the maximal rise in the total blood sugar at the end of the infusion apparently is due to the glucose resulting from the rapid metabolic conversion of fructose to glucose. 4.4. Fructosuria occurred in all cases studied. The average amount of reducing substances recovered was 2.3 Gm., or the equivalent of a loss of 4.6 per cent of the fructose infused.The range of urinary mellituria was between 0.96 and 7.4 Gm. Therefore, the tolerance rate (rate of infusion of a sugar without mellituria) for fructose is below 0.76 Gm. per kilogram per hour. 5.5. The observation of fructosuria associated with low levels of fructosemia indicated a low renal threshold for fructose in human subjects. In rabbits and dogs, after the injection of fructose intraduodenally, there was a marked withdrawal of fructose from the blood passing through the liver. Estimations of the fructose in samples of blood collected simultaneously from the femoral artery and vein after the injection of 3 Gm. of fructose per kilogram of body weight in dogs showed a direct utilization of fructose by the muscle of the extremity. These data offer important confirmation of in vitro studies reported by others. In view of the rapid utilization of fructose by human beings, its use in medical and surgical conditions which require rapid glycogen formation, low levels of hyperglycemia, active protein sparing, and antiketogenic activity, should be entertained. Fructose may prove to be a valuable carbohydrate in the management of the diabetic patient, and in the treatment of the patient with low glycogen reserves.

Metabolism of fructose by the liver of diabetic and nondiabetic subjects.

Summary and ConclusionsThe metabolism of fructose in the liver was investigated by hepatic vein catheterization studies in 3 diabetic patients deprived of insulin and in 3 non-diabetic subjects. (1) There was a large hepatic uptake of fructose during the period of intravenous administration in both diabetic and non-diabetic subjects. (2) In all but one case there was a large hepatic output of pyruvic and lactic acid during the fructose infusion. The liver of one diabetic patient in ketosis continued to remove pyruvic and lactic acid from the blood; hepatic glycogen depletion may have accounted for this divergent result. (3) In half the cases (2 diabetic patients and 1 non-diabetic subject) the output of glucose by the liver was increased during fructose administration. (4) In the absence of ketosis, the liver of the diabetic subject without insulin, therefore, metabolized fructose in a manner similar to that of the liver of the non-diabetic individual. The presence of ketosis, however, was accompanied by ...

Comparative utilization of fructose and glucose given intravenously.

SummaryIn 10 experiments on human subjects comparative intravenous injections of 10% glucose and 10% fructose were carried out. Even at rapid rates of infusion very little fructose appeared in the urine as compared to the amount of glucose. Diuresis was also less pronounced with fructose. Moreover, the fructose infusions were not followed by either hyperglycemia nor by an excessive rise in the blood fructose level, thus indicating a more rapid utilization of fructose and presumably more rapid glycogenesis.